Hello. I have the feeling of a pebble or a bone chip floating around the front of my knee. It hurts when I bend it past 90 degrees, and I have to massage the side of knee for a second, then it will bend. When I climb stairs, or do squats, it feels like the "stone" is just behind kneecap, and it really hurts. I haven't ever had a knee injury, but I am 43 and have been very active.